1. Field of the Invention
The present invention relates to a server device, an image forming apparatus, and an image processing system those capable of providing a smooth printing environment even in a thin client environment.
2. Description of the Related Art
In response to requests for a secure desktop environment with the increasing security needs, a thin client system has attracted attention in recent years. The thin client system is a generic name of a system including one or more client terminals and a server device in which the client terminals is allocated with the minimum number of functions while the server device manages all the resources such as applications and files. In the thin client system, because all the resources are managed by the server device, even a print job is executed by the server device. For example, when a print job is to be executed, the server device transmits printing instruction data including print data to a printer via a network thereby causing the printer to print out the print data.
Meantime, with requests for improvement in printing quality, a volume of printing instruction data has been getting larger in recent years. When a large volume of printing instruction data is transmitted, an efficient transmission of the printing instruction data in a network is desired. Therefore, to reduce network traffic, there has been developed such a solution that printing instruction data is compressed to reduce its data volume, and a printer expands the compressed printing instruction data and prints out print data. Related technology has been disclosed in, for example, Japanese Patent Application Laid-open No. 2002-292943 and Japanese Patent Application Laid-open No. 2002-240368.
FIG. 16 is a block diagram of a schematic configuration of a printer disclosed in Japanese Patent Application Laid-open No. 2002-292943 as an example of a conventional image forming apparatus. The printer can transfer image data either with or without involving an expanding unit 1403 provided on a data path connecting between a receive buffer 1401 and an image buffer 1402. Therefore, the printer can select an optimum data path depending on whether the received image data is compressed data and a volume of the image data. Thus, it is possible to reduce the involvement of a central processing unit (CPU) when the image data is transferred between the buffers.
However, in the technology disclosed in Japanese Patent Application Laid-open No. 2002-292943, the compression is applied to only the image data because it has a large data volume, i.e., the compression is not applied to the whole printing instruction data. In other words, the whole printing instruction data including data on a graphic and a text, information in a Printer Job Language (PJL), and the like is not compressed before sending the printing instruction data to a command interpreting unit 1404. For example, when the printing instruction data includes only text data, the printing instruction data is transmitted without being compressed. To provide a smooth printing environment in a thin client environment, it is necessary to reduce network traffic in such a manner that data to be transmitted from a server device to the printer is compressed thereby reducing a volume of the data. Therefore, when the compression is applied to only a large volume of image data, it is difficult to provide a smooth printing environment in the thin client environment.
Furthermore, in an apparatus disclosed in Japanese Patent Application Laid-open No. 2002-240368, upon receiving data on a still image in an arbitrary compressed file format from a higher-level device as input information, the apparatus converts the input data into bitmap data, and outputs the bitmap data to an image forming engine. Thus, this apparatus can expand the input data depending on the compressed file format employed to compress the input data.
However, the apparatus disclosed in Japanese Patent Application Laid-open No. 2002-240368 is designed to print out a high-resolution still image at high speed, and is not considered for a print job in a thin client environment at all. Therefore, the apparatus is not for providing a smooth printing environment in the thin client environment.